Acute Decompensated Heart Failure in an Elderly Patient: A Rare Presentation of Toxic Nodular Goiter

BACKGROUND Toxic nodular goiter is a common cause of hyperthyroidism in older adults, but its association with acute heart failure is rare. CASE REPORT We present the case of an 87-year-old woman with a history of heart failure, atrial fibrillation, chronic kidney disease, and multinodular goiter, who experienced worsening heart failure symptoms, including dyspnea and significant bilateral lower limb edema. Initial evaluation revealed elevated NT-proBNP levels, pulmonary edema, and atrial fibrillation, suggestive of acute decompensated heart failure. Thyroid function tests unexpectedly showed elevated free T4 and suppressed thyroid-stimulating hormone, consistent with hyperthyroidism. A Tc-99m thyroid scan confirmed toxic multinodular goiter. Notably, ultrasound evaluation showed that the largest nodule (4 cm) remained stable in size over 6 months and fine needle aspiration indicated a benign lesion, ruling out malignancy. The patient's hyperthyroidism was likely due to the transition of previously non-functioning thyroid nodules into autonomously functioning nodules, possibly influenced by her advanced age and longstanding goiter. Her acute heart failure was exacerbated by hyperthyroidism and pre-existing atrial fibrillation. Treatment included optimized heart failure therapy and carbimazole for hyperthyroidism, resulting in significant clinical improvement. CONCLUSIONS This case highlights the importance of considering thyroid dysfunction, including toxic nodular goiter, as a potential cause of acute heart failure exacerbation in elderly patients. Early diagnosis and appropriate treatment are crucial to improving outcomes in such complex clinical presentations.